Set the CSV output to an empty string for null values

CHANGELOG.md

@@ -54,6 +54,7 @@ The admin UI is removed and unusable in this release. The `[admin]` configuratio
 - [#8315](https://github.com/influxdata/influxdb/issues/8315): Remove default upper time bound on DELETE queries.
 - [#8066](https://github.com/influxdata/influxdb/issues/8066): Fix LIMIT and OFFSET for certain aggregate queries.
 - [#8045](https://github.com/influxdata/influxdb/issues/8045): Refactor the subquery code and fix outer condition queries.
+- [#8343](https://github.com/influxdata/influxdb/issues/8343): Set the CSV output to an empty string for null values.
 
 ## v1.2.3 [unreleased]
 

services/httpd/response_writer.go

@@ -145,6 +145,11 @@ func (w *csvFormatter) WriteResponse(resp Response) (n int, err error) {
 			}
 			for _, values := range row.Values {
 				for i, value := range values {
+					if value == nil {
+						w.columns[i+2] = ""
+						continue
+					}
+
 					switch v := value.(type) {
 					case float64:
 						w.columns[i+2] = strconv.FormatFloat(v, 'f', -1, 64)
@@ -160,6 +165,8 @@ func (w *csvFormatter) WriteResponse(resp Response) (n int, err error) {
 						}
 					case time.Time:
 						w.columns[i+2] = strconv.FormatInt(v.UnixNano(), 10)
+					case *float64, *int64, *string, *bool:
+						w.columns[i+2] = ""
 					}
 				}
 				csv.Write(w.columns)

services/httpd/response_writer_test.go

@@ -0,0 +1,61 @@
+package httpd_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+	"time"
+
+	"github.com/influxdata/influxdb/influxql"
+	"github.com/influxdata/influxdb/models"
+	"github.com/influxdata/influxdb/services/httpd"
+)
+
+func TestResponseWriter_CSV(t *testing.T) {
+	header := make(http.Header)
+	header.Set("Accept", "text/csv")
+	r := &http.Request{
+		Header: header,
+		URL:    &url.URL{},
+	}
+	w := httptest.NewRecorder()
+
+	writer := httpd.NewResponseWriter(w, r)
+	writer.WriteResponse(httpd.Response{
+		Results: []*influxql.Result{
+			{
+				StatementID: 0,
+				Series: []*models.Row{
+					{
+						Name: "cpu",
+						Tags: map[string]string{
+							"host":   "server01",
+							"region": "uswest",
+						},
+						Columns: []string{"time", "value"},
+						Values: [][]interface{}{
+							{time.Unix(0, 10), float64(2.5)},
+							{time.Unix(0, 20), int64(5)},
+							{time.Unix(0, 30), nil},
+							{time.Unix(0, 40), "foobar"},
+							{time.Unix(0, 50), true},
+							{time.Unix(0, 60), false},
+						},
+					},
+				},
+			},
+		},
+	})
+
+	if got, want := w.Body.String(), `name,tags,time,value
+cpu,"host=server01,region=uswest",10,2.5
+cpu,"host=server01,region=uswest",20,5
+cpu,"host=server01,region=uswest",30,
+cpu,"host=server01,region=uswest",40,foobar
+cpu,"host=server01,region=uswest",50,true
+cpu,"host=server01,region=uswest",60,false
+`; got != want {
+		t.Errorf("unexpected output:\n\ngot=%v\nwant=%s", got, want)
+	}
+}